V6/4HP20 Owners: A Cautionary Tale

[CitroJim]

I spoke to a CCC member last evening who has had the most unforunate experience of loosing all his gearbox oil due to failing sealing washers on the Banjo Union on the main oil supply pipe on the side of the gearbox. He was unaware of the leak whick pumped his 'box dry in 150 miles or so

The 4HP20 gearbox gives no real signs of oil loss until it is empty and then it complains but it's too late

This is a fairly common area for leaks and is caused by slow corrosion of the aluminium washers each side of the Banjo.

It is worth checking on a regular basis to ensure there are no weeps from the union; just look up at it from the NS wheelarch. Any leaks will be very obvious as the side of the gearbox and mudshield will be wet. This is one of my weekly checks.

I've had it happen on New V6 but luckily caught it very early.

The member in question is going to have his gearbox rebuilt as it's now very noisy despite appearing to work OK. Sounds like a bearing or two has suffered.

[jgra1]

thanks for that Jim.

J

[Stempy]

I fitted mine with copper washers as the alloy ones seem a bit feeble.

[Dommo]

Seems to be a common issue, I recall DHallworth having the same issue.

[bl4ck clio]

"banjo union"

can someone explain where is the placement on 4HP20?
with some photo will be more clear....

thanks.

[RichardW]

It's on the end of gearbox, visible from the LH wheel arch above the drive shaft. Picture in this post: 4HP20 Oil Banjo

[CitroJim]

And here it is in this thread...



This was a picture of my own car on the verge of leaking a lot!

[DHallworth]

Seems to be a common issue, I recall DHallworth having the same issue.

Yup, caught early enough thankfully

David.

[Mandrake]

I spoke to a CCC member last evening who has had the most unforunate experience of loosing all his gearbox oil due to failing sealing washers on the Banjo Union on the main oil supply pipe on the side of the gearbox. He was unaware of the leak whick pumped his 'box dry in 150 miles or so

The 4HP20 gearbox gives no real signs of oil loss until it is empty and then it complains but it's too late

This is a fairly common area for leaks and is caused by slow corrosion of the aluminium washers each side of the Banjo.

Sorry to hear that this happened, I know I would have been gutted if it happened to me. Fortunately that's one of the problems that my 4HP20 hasn't had yet... its dry and dirty in that area with no sign of oil loss at all.

The member in question is going to have his gearbox rebuilt as it's now very noisy despite appearing to work OK. Sounds like a bearing or two has suffered.

What sort of noise was it making exactly ? I still think my gearbox is quite noisy under some conditions... it seems to be silent and smooth when the torque converter clutch is open but when its closed and you're trying to pull at low revs there is a definite dry bearing sound that the pessimist in me says is probably the neck bearing on its way out...the clutch locking up probably pulls the axial alignment of the shafts slightly thus moving the shaft relative to the bearing. (If there is slack in the bearing that allows the TC to tilt when the clutch is released...)

How low does the oil need to be before there is bearing damage ? When I did my first oil change - which was some weeks after it first started making a groaning noise, maybe 6 months after I got the car, the oil level was about 700ml too low based on measuring what came out and what went back in again topping up to the correct levels... It was well below the low mark, just barely above the end of the dipstick. As far as I can tell the gearbox is not losing any oil so it could have been low in oil level for some time before I got it...

Sadly I did not check the oil level when I first got the car, nor can I remember whether there was any sign of that dry bearing noise at that time.

[CitroJim]

The HP20 will not be too sensitive to slightly low oil Simon as the oil pickup is very low in the 'box. It's only a gnat's cock above the level of the drain plug...

Noise? It'll be screeching and squealing most likely due to the TC neck bearing being welded and spinning in its housing. Also the output shaft bearings suffer similarly. I have one here that's fused together and that was spinning it in housing.

Even a good HP20 is noisy. Drive a V6 with a manual box and the silence is deafening! The HP20 makes quite a lot of what I'd describe as white noise for want of a better term - a general mechanical din.

[Mandrake]

The HP20 will not be too sensitive to slightly low oil Simon as the oil pickup is very low in the 'box. It's only a gnat's cock above the level of the drain plug...

That's interesting by the way - where is the oil filter in the gearbox ? Is the filter element right at the bottom near the drain plug where the oil is being drawn in for the pump ? What I'm wondering is if the filter gets clogged due to dirty oil, is the clogged side of the filter right at the bottom of the gearbox, thus potentially some of what's clogging it would be drained out when doing an oil change ?

In other words are multiple oil changes like I've done likely to have any effect on unclogging the filter or do you think it would remain just as clogged if it were clogged ?

Noise? It'll be screeching and squealing most likely due to the TC neck bearing being welded and spinning in its housing. Also the output shaft bearings suffer similarly. I have one here that's fused together and that was spinning it in housing.

So you think if any of the bearings were turning in their housing it would be a very obvious noise, not something subtle like what I hear ? I don't have much experience with autos the only other ones I've driven are the 4HP14 and they were pretty quiet.

When I drove David's donor V6 I couldn't really tell how noisy (or not) the gearbox was because of the rough road conditions - I couldn't hear any noise from my gearbox driving the same stretch of road either, but on smoother more quiet surfaces like pulling into our parking area I do hear a strange noise.

[CitroJim]

The oil filter and intake are one piece Simon and I suppose the bottom of the filter sits about an inch above the floor of the 'box.

The filter therefore will be submerged and I can see that multiple changes will shift out some of the rubbish in it...

You know when a bearing is spinning it it's housing, believe me. It's not a nice or quiet sound.... It'll set your teeth on edge.